Method for the treatment of phenol-bearing liquors



JQ A. SHAW Nov.- 17, 1931.

METHOD FORTHE TREATMENT oF PHENOL BEARING LIQUoRs F11-ed May 27 .i925 :5 sheets-sheet 1 NN QN lNvENToR WQ-k mk 59W' Hwmrew H36 ATToRNEYs WT@ UDCAOO 20min-l0 um am Nw Dhu @N @N KN mwommv. N. uwov. n ozmzamn munie NM DUNTJDN EOFDJO D JOZMIl QH,

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METHOD FOR THE TREATMENT OF PHENOL BEARING LIQUORS Filed May 27, 1926 3 Sl'leets-Sheei.` 2

,INVENTOR `J my; nu, se,

Nov. 17, 1931. J. A. SHAW 1,832,140

METHOD FOR THE TREATMENT OF PHENOL BEARING LIQUORS Filed May 27, 1925 3 Sheets-Sheet 3.

INVENTOR W5- ATTORNEYS Patented Nov. 17,4931

UNITED STATES lPATI tla'r OFFICE( JOSEPH ALLAN SHAW, or PITTSBURGH, PENNSYLVANIA, -ASSIGNOR To THE HOPPERS COMPANY, or PITTSBURGH, PENNSYLVANIA, A' CORPORATION OP PENNSYLVANIA" 1f tar.

METHOD POR THETHEATMENT or PHENOLBHAHING LIQ'UORS Application ined May 27,

This invention relates to the treatment-of phenol-bearing liquors, and is of particular value in the treatment of liquors produced in the recovery of ammoniaffrom Icoal'gas whereby removal of the contained phenol is effected.

It has become important, from the standpoint of public health and convenience, to avoid contamination of rivers, lakes and the like with phenol, since it is almost impossible to remove the phenol by ordinary meansif it gets into municipal watersupply systems. It is becoming increasingly necessaryfor gas plants to remove phenol from wastes in which it is contained. The present' invention provides for such removal at a minimum of Vexpense, and it is attended with-numerous ad# vantages over the present methods employed.

It is common to treat phenol-,bearing liquors with benzol, which is immiscibl'e therewith and which extractsv the phenol. This extraction is usually practiced on `the undistilled ammoniacal liquors.l The phenol -is then removed from the benzol by treatment with caustic soda, thus forming sodium phenolate, and the phenol is subsequently sep,- arated by acidification. While benzol is an excellent solvent for phenol, it also is asolvent for any tar that maybe present inthe liquor, and after only a moderate periodof use it becomes so fouled with such tar that it must be discarded and' replaced with fresh benzol.

I employ a phenolabsorbing petroleum distillate, such as kerosene, for the phenol extraction. I have found that even though kerosene is not as powerful a solvent'for phenol as is benzol, it possesses'numerous important advantages over benzol4 vvhich'renderV it superior for phenol extraction. It is less soluble in water than benzol, and consequently lossesv due to solution ofthe extraction agent in either the waste or the caustic solution are decreased. Tar ismuchlesssoluble in kerosene than in benzol, yand therefore `kerosene may lbe used for longer periods than benzol without undue` contamination by dissolved The use of kerosene is attended with much less loss dueto evaporation, and the lire hazards are greatly minimizedzby itSuse,

1926. .SerialNm 112,041.

Kerosene is a more available and a less ex- A' employ porous means, such as the wellknown Filtros blocks or plates; alundum plates, fabric dilfusers, or the like, through which the kerosene is introduced into the liquor or the caustic solution.

vI have further discovered that the ten'd-l Y ency 'oftar to coagulate in the distillation of ammonia from gas vliquors results in a reduction of the amount of tar dissolved by the kerosenelor other solvent employedif the extraction of phenol is practiced uponD the wastes from ammonia stills, as compared to the oldpracticev oftreating the ammoniacal liquors before distillation, when the tar is present in a more or less colloidal state. I

therefore kprovide to treat the liquors to co- .n

agulate thek tar, and thereafter treat thezliquorsv to remove phenol therefrom.

Instead of using sulphuric acid, ywhich, is relatively costly, for the libera-tion of phenol from the' so'dium'phenolate solution, I prefer to treat such solution with carbon dioxide.l The carbon dioxide maybeconvenientlyy and cheaply found` in fluegas and A'may also be used to acidify thel still waste `before Vit is treated with the kerosene. AThese ycarbon-,di-

oxide treatments are vpreferably accomplished in tanks provided with porous diffusers which may be similar in character to above mentioned. y

. The use. ofA ue gas is of particular value in a gas plant` for a largelamount of such gas is available. The; presence ofv nitrogen in the flue gasis unimportant as it is inert y and simply passes through the liquids' being treated.- y

the diffusers l' i Cl'i The accompanying drawings illustrate more or less diagrammatically va preferred embodiment of the invention with certain modifications of portions of the apparatus.

In the drawings- Figure 1 is a diagrammatic view of an apparatus for the treatmentof still waste or other phenol-bearing liquor;

f ,Figure 2 is a side elevation, partly broken away, of a portion of the apparatus` shown in Figure l;

Figure 3 is a horizontal section taken on the line III-III of Figure 2;

Figure 4 is a view similar toFigure 2 but showing a modied form of apparatus; and 1 y Figures 5 and 6 are views corresponding to the bottom portions of Figures 2 and 4.

but showing modified diffusion apparatus.

In practicing the invention 'I prefer totreat the liquorsfromthe ammonia stills. Such liquors, when fresh from the lime leg of the stills, 4may contain varying, percentages of CaCh, Ca(CNS)2, CaS, CaSOi', CaS2O3, Ca2Fe(CN)G, Ca(OIcI)2, CaCOS, NIILOH, slight amounts of tarry materials or tar constituents, any impurities introduced in the liming process, and phenol. The

.phenol is usuallycombined with'calciurn in the form of calcium phenolate, @MUSEI-,Ola The effluent liquors may .be treated directly orthey may be decanted after settling to effect separation Vof a large portion of the suspended materials. YVhether it is `subjectedto this deca'nting treatment or not, the effluent is supplied through a conduit 1 to acidifying tanks C1n and C? arranged for batch treatment. Y Valves 1a are provided in the conduit 1 for controlling the flow tothe acidifying tanks.

Each of the acidifying tanks is provided with a plurality of porous diffusers 2 which are connected through conduits 3 to amanifold l which is connected to a` source 57 of carbon vdioxide gas asV hereinafter described. 'Ihe diffusers 2 are preferably textile fabric tubes through which the carbon dioxide may pass in finely divided Vform to the liquors in the acidifying tanks. The fabrictubes are vibratile and are therefore effective for discharging the gas into the liquors over a continued perid of time without yclogging up. These diffusers aremore particu"- larly described and claimed in the copending application. of Gilbert E. SeiLSerialNo. 21,978, filed April 9, 1925. It will be understood, of course, that various otherporous d-iffusers maybe used if desired.

The reactions which occur inthe acidifying tanks C1 and C2 include the following:

(1j oaon i+ooz=oaooi+m (2)' 2 NHioHa-oopmnazooaa-Hio;' (3) caooi-l-C02-H&no=oa(noon2;andv ,l (4) lCa(C`H5O)n-l-CO2+HaO=CaC,O3-l-2CaH5OH After carbonating a batch of` the waste liquors until the above reactions are completed, that is, until the waste is acidified, the C()2 is shut off and the liquid is allowed to settle. VThe insoluble materials settle at the bottom of the tanks and may be removed at suitable intervals through drains 5. The supernatant liquor containing the phenol is decanted by suitably manipulating valved manifolds 6 and is allowed to flow through a conduit 7. at a. convenient rate. If liquors which are already acid in character are to be dealt with, the acidification may be omitted and the liquors introduced through a .conduit 7 a.

The acid liquors which are taken from the tanks C1 and C2 or supplied through the conduit 7a are carried through the conduit 7 to a washer W. The washer comprises a cylindrical shell provided with a porous diffusion means 8 near the bottom thereof. Said diffusion means may comprise a Vlayer of porous ceramic blocks, such as Filtros blocks, a layer of fabric, the above described vibratile fabrictubes, o r any other suitable diffusion means. rIhe diffusion means illustrated in thewasher W is generally similar to that hereinafter described in connection with the stripping tank.

The purpose of the washer W is to introduce kerosene in finely divided form to the liquors supplied through .the conduit 7 Kerosene is withdrawn froma storage tank 9 and flows through a conduit 10 into-a sump 1l'. VThissump is provided vwith 'a plurality of baffles 12 which are effective for removing any sediment from the kerosene. The kerosene is withdrawn from the sump through a conduit-'13 havingy a pump 14 therein and is introduced to the washer W below the porous diffuser 8. As it passes upwardly through the the diffuser it comes into contact with the phenol-bearing liquors in a very finely divided state. It is found that this is conducive to a very high efficiency of contact between the kerosene and theliquors and, consequently, a high rate of phenol extraction.

I have observed that the amount of phenol extracted by the kerosene is roughly proportional to the amount of'phenol originally present in the liquors. The passage of four -ly with various items of cost, the degree of Vdep'henolization necessary, and the like.

f As the introduction of kerosene to the liquors is continued, a substantial portion of the phenol will' dissolve in the kerosene, which, being lighter than the liquors, will rise to the'top of thewasher W. This phe- .nolized kerosene is taken offthrough a convil() duit having a :valve 16 therein. 'Preferably this removal is continuous and the de'n vphenolized waste is withdrawn/'through a sealed drain 1'( and emptied into a sump 1S. The sump 18 is provided with a plurality of baliles 19 which assist in causing any kerosene that may have been entrained `with the dephenolized waste to rise to the top ofthe liquid in the sump 18. The waste, `freed of kerosene, is taken up through a conduit 20 and discharged into a sewer 21, while the supernatant kerosene drains through a: conduit 22 into a sump 23. The phenolized kerosene taken from the washer through the conduit 15 is also discharged into thisl sump. The sump 23 is provided with battles 211 which effectively retain any sediment or waste liquors entrained by the enriched kerosene. The kerosene is withdrawn from the sump 23 through a conduit 25 having a pump 26 therein and is discharged in a stripper S. The stripper S comprises an outer. shell having a porous false bottom P below which the phenolized kerosene is introduced through the conduit 25. A'solution of caustic soda is maintained in the stripper abovethe .false bottom P, andthe purpose of the false bottom is to introduce the phenolized kerosene toV such caustic solution' in al very finely divided state. e V

The construction of the stripper S is shown in detailfin Figures 2 and-3.` The false bottom P consists of porous blocks 27 carried by suitable supporting members. vFor use in the stripper I prefer to use porous blocks of aluminium oXid, such as'the' well v known alundum blocks, as this material is resistant to the action ofthe caustic solution. In the washer W,' however, 'the Vwell known Filtros blocks are preferred as-there is no caustic present in the'washer andthe Filtros blocks are readily obtained in a highly porous and open grade especially suitable for my purpose.

The blocks are cemented together as indicated at 27 so that all the phenolized kero sene introduced below the false bottom Vmust pass through the blocks and be diffused thereby.

Figures 5 and 6 show slightly modified forms of diffusers for use at the bottom of the washer. In Figure 5 there is illustrated a flat vibratile metallic fabric 28 which extends across the bottom of the stripper and is eective for breaking up the phenolized kerosene into a state of tine division. In Figure 6 tu-V bular diffusion means 29 are illustrated. The apparatus shown .in Figures 5 and 6 is described and claimed infthe'cop'ending application of David L. Jacobson. Serial No. 119,176, ined June es, i926.

` When the finely divided phenol-bearing kerosene passes through the diffusionk means, it comes into contact with the caustic solution in the main body yof the stripper S. l.This

lution byientrainment with the kerosene, I

caustic solution `is suppliedy throughZ a "conduit 30 lfrom asupplyftank 31 and itremains above the porous false bottom or other Vdiffu- Y sion means employed, due to the positive l pressure ofthe kerosene being forced through 'f the diffuser. f y y The phenol'carried by the kerosene reacts withthe caustic according to the'following equation: c g5) ourson NaoH=NaccH5o y H20. The sodium phenolate dissolves in the aqueous solution. Y I

Sincethekerosene is lighterv than the caustic solution, it rises tothe top of the stripper, freed from its phenol byk contact with the causticsolution, and -may be withdrawn 'for further use. n 1 y In order to prevent loss of the aqueous=so- Yprovide means for baffling the kerosene in the course of its flow from the stripper. Referring' to Figure 2, it will be seen` .that the top ofthe shell 61, is not truly horizontalbut is slightly inclined.V This means that as jthe .kerosene reaches the top` of the shell it flows over at one sider` only; as the apparatus is shown in the dra-wings, it will flow over the left hand side. l The kerosene which 'flows over the-top of the shell 61 is caught'in an annular passage i formed by an upstanding wall 33 andan out.,

wardly extending bottom V34. lThe top, o-f the wall 33 is also inclined to the horizontal, and in-this case vthe kerosene7 as it'leavesfthe annular duct, will flowover the portion ofthe duct lying atthe 'right hand side of the apparatus, as viewed in ,Figure 2. kkThis means that .the kerosene must flow( substantially half way around the stripper beforeit passes over the wall 33 into an outer annular duct formed by the outwardly extending bottom 34 and an upstanding wall 35. The kerosene is permitted tok How fromthis'outer duct through a.' conduit 32. and, as shown in Figure 2this lies at the left hand side of the apparatus as viewed in the drawings, so that 'in order to reach it the kerosene must again travel half way around .the stripper. `During this tortuous course whatever caustic` solution ma;T be entrained with the kerosene is separated therefrom by gravity and flows back to the stripper through openings 36 in the wall 33 and the shell 61. I'have indicated by a chain line L the general level of the lkerosene at the top of the stripper. It will be seen that theupstanding walls over which the kerosene must lio-w lie partly above and partly below .this line, so that the kerosene is forcedto take a path as above described in leaving the stripper. The conduit 82 leads back to the sump lllfrom which the kerosene may be again Vwithdrawn and used'in the washer on asubsequentb'atch of phenol-bearing liquor.

-. Figure .4 illustrates a modified form of 'stripper in which `corresponding parts have been given the same reference character with an a sulfixed thereto. In this embodiment of the stripper,the shell is flared outwardly near the top and two bailes 39 and 40 are provided. "Ihesebaies have their upper edges at substantially the same level, and their lower edges do not meet the outwardly 'liared shell portion 342"l except for whatever supporting means may be necessary. The kerosene flows over the baffles 39 and 40, and during this time the caustic solution has an opportunity to separate by gravity and flow back to the main body of caustic in the stripper through the spaces below the bafiles.

The kerosene leaves the stripper through openings 38 leading to a manifold 37 which is connected to the conduit 32a.

When the caustic solution in the stripper nears its saturation point for phenol content, it is withdrawn through a conduit 41 to a tank 42 where it is held pending f urther treatment. Fresh caustic is Ythen admitted to the stripper S from the supply tank 3l. When it is desired to recover the phenol from the solution in the tank 42, the solution is pumped by means of a pump 43 in a conduit 44 into ,a carbonating tank i C3. This carbonating tank is provided with a plurality of porous aerators 45 which areconnected by conduits 46 toa manifold 47 which is connected to a sourcerofv CO'Zas hereinafter described. y

Phenol is liberated in the carbonating tank C3' accordingto the following reaction:

irWhen this reaction is substantially complete, the liquid in the tank C3A is allowed to ticizer through a vconduit 54, and is agitated vwith the carbonate solution until the following reaction is completed: Y

7) Nmco3+oa om2=2Naon+eaoo3 The calcium carbonate precipitates and is ydrawn off as a sludge through a conduit 55. 'The caustic solution 1s permitted to flow through a conduit 56 back to the supply tank 31 to renew the caustic solution therein. Additions of fresh caustic may be made to the supply tank 31 as required. The strength of the caustic solution is preferably the highest obtainable in the recausticizer, and may be made even higher by adding caustic soda to the tank 31. v

motionof this absorption. The purified flue gas is withdrawn from the top of the tower T through a conduit 59 by means of a pump 60 and is pumped to the manifolds 47 and 4 through a conduit 62.

In the 'above description I have set out the preferred form of my invention, wherein kerosene is used for absorbing the phenol from the gas liquors, and wherein carbon dioxide is used for acidifying, and caustic soda is used in the stripper. It will be understood that other phenol absorbing petroleum distillates may be used, as, for example, light fuel oil, naphtha or gasolene.

Instead of using caustic soda in the stripper, I may employ other substances, such as potassium hydroxide or calciumY hydroxide.

Certain parts of my invention may be advantageously employed where an aci'dilier other than carbon dioxide is employed. For example, 'sulphuric acid may be used in connection with certain of the features of my invention. However, flue gas provides one of the most economical sources of acidifier and is, therefore, preferred.

I have illustrated and described a preferred embodiment of my invention and one manner of practicing it, but it' will be understood that the invention is not limited to the described embodiment as it may be otherwise embodied or practiced within the scope of the following claims.V

I claim:

1. In a method of treating aqueous phenolbearing'liquor, the'step consisting in treating the liquor with a phenol-absorbing petroleum distillate.

2. In a method of treating aqueous phenolbearing liquor, the step consisting in treating the liquor with a phenol-absorbing petroleum distillate lin a finely divided state.

3. In the treatment of gas liquor to remove i tar acid therefrom, the step which comprises treating the liquor with a petroleum distillate after removal of ammonia from the liquor. f 4 i 4. In the treatment of gas liquor to remove tar acid therefrom, the step which Vcomprises treating the liquor with a petroleum distillate after removal of ammonia, the distillate beingsupplied to the liquor in a linelydivided state.

i Y5,. In a method of removing phenol from gas liquor, the steps -consistingin treating the liquor With a phenol-absorbing petroleum distillate to remove phenol therefrom, and treating the phenol-bearing distillate with caustic soda to form sodium phenolate.

6. The process of removing tar acid from aqueous liquor containing it which comprises continuously recirculating a hydrocarbon oil having a substantially dierent specific gravity therefrom through a cycle comprising an absorption stage in which it is brought into intimate contact With the liquor and a regeneration stage in Which taracid removed from the aqueous liquor in said absorption stage is in turn removed from said hydrocarbon oil.

7. The process of removing tar acid from aqueous liquor containing it which comprises continuously recirculating a hydrocarbon oil having a substantially different specific gravity therefrom through an absorption sta-ge in Which it is brought into intimate contact With the liquor and a regeneration stage in which it is brought into intimate contact With an aqueous liquid of strongly absorbent nature With respect to tar acid.

8. The process of removing tar acid from aqueous liquor containing it Which comprises continuously recirculating a petroleum distillate oil through a cycle comprising an absorption stage in which it is brought into intimate contact With the liquor, and a regeneration stage in Which tar acid removed from the aqueous liquor in said absorption stage is in turn removed from said oil.

9. The process of removing tar acid from an aqueous liquid containing the same, which comprises continuously introducin said liquid and a phenol-absorbing petro eum distillate to contact with each other, and then .Y

separating said liquid and said distillate.

10. The method of removing tar acid from an aqueous liquid containing it Which comprises establishing a substantially continuous counter-current flow of said liquid and a treating liquid comprising a phenol-absorbing petroleum distillate, and segregating the treated liquid and the treating liquid.

In testimony whereof I have hereunto set my hand.

JOSEPH ALLAN SHAW. 

